Ultrasound-Assisted Thoracic Paravertebral Block Reduces Intraoperative Opioid Requirement and Improves Analgesia after Breast Cancer Surgery: A Randomized, Controlled, Single-Center Trial

Abstract

Objectives: The contribution of ultrasound-assisted thoracic paravertebral block to postoperative analgesia remains unclear. We compared the effect of a combination of ultrasound assisted-thoracic paravertebral block and propofol general anesthesia with opioid and sevoflurane general anesthesia on volatile anesthetic, propofol and opioid consumption, and postoperative pain in patients having breast cancer surgery.

Methods: Patients undergoing breast cancer surgery were randomly assigned to ultrasound-assisted paravertebral block with propofol general anesthesia (PPA group, n = 121) or fentanyl with sevoflurane general anesthesia (GA group, n = 126). Volatile anesthetic, propofol and opioid consumption, and postoperative pain intensity were compared between the groups using noninferiority and superiority tests.

Results: Patients in the PPA group required less sevoflurane than those in the GA group (median [interquartile range] of 0 [0, 0] vs. 0.4 [0.3, 0.6] minimum alveolar concentration [MAC]-hours), less intraoperative fentanyl requirements (100 [50, 100] vs. 250 [200, 300]μg,), less intense postoperative pain (median visual analog scale score 2 [1, 3.5] vs. 3 [2, 4.5]), but more propofol (median 529 [424, 672] vs. 100 [100, 130] mg). Noninferiority was detected for all four outcomes; one-tailed superiority tests for each outcome were highly significant at P<0.001 in the expected directions.

Conclusions: The combination of propofol anesthesia with ultrasound-assisted paravertebral block reduces intraoperative volatile anesthetic and opioid requirements, and results in less post operative pain in patients undergoing breast cancer surgery.

Trial registration: ClinicalTrial.gov NCT00418457.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Ultrasound image of thoracic transverse process.

Transverse processes (TP) appear square and lie deeper than the ribs. The distance between the skin and the TP was measured and 5 mm added (distance A). The distance between the skin and the pleura was also measured (distance B). Distance A was used as the reference for needle depth, and the needle was not advanced beyond distance B.

Fig 2. Consolidated Standards of Reporting Trials (CONSORT) flow diagram depicting subject progress through the phases of the study.

PPA group: thoracic ultrasound-assisted thoracic paravertebral blocks at the T1–T5 thoracic levels with propofol-based general anesthesia; GA group: sham subcutaneous local anesthetic injections with sevoflurane-based general anesthesia and opioid-based analgesia (GA group).

Fig 3. Boxplots comparing randomized groups for each primary outcome.

The box represents the interquartile range, the horizontal line the median, the whiskers extend to the high and low values within 1.5 interquartile ranges of the box, the circles represent values beyond 1.5 interquartile ranges of the box and the diamond represents the mean.

Fig 4. Superiority plots showing the ratios of mean ranks (98.75% confidence intervals, CIs) between the regional and general groups for each primary outcome.

Parentheses indicate two-sided 98.75% CIs estimated using bootstrap resampling. Joint hypothesis testing of the four primary outcomes indicated effectiveness of paravertebral analgesia over general anesthesia, as all four CIs lie within the superiority regions: less pain, less intraoperative fentanyl use, less volatile anesthetic use, and increased propofol use.